It is common in a system of components to coordinate the actions of the components using trigger signals. Examples of components that may be coordinated using trigger signals are numerous and include sensors, actuators, computational devices, application controllers, computer systems, measurement instruments, devices under test, etc.
Trigger signals may be distributed to a set of components using a trigger bus. For example, a trigger source may apply a trigger signal to a trigger bus and the trigger signal propagates to each component connected to the trigger bus. The times that the components on the trigger bus receive the trigger signal may depend on the distances between the components and the trigger source. For example, components farther away from the trigger source receive the trigger signal later than components closer to the trigger source due to propagation delay on the trigger bus. A trigger bus topology may offer the benefit of relatively easy system modifications. For example, a new component may be relatively easy to add to a trigger bus. Unfortunately, the variation in times that the components in a bussed topology receive a trigger signal may prevent precise coordination of the actions performed by the components.
Alternatively, trigger signals may be distributed to a set of components using point-to-point trigger signal line connections between a trigger source and each component. Point-to-point signal line connections from a trigger source to a set of components may be referred to as a star topology. A star topology enables equalization of the propagation delays of the trigger signal by selecting the lengths of the signal lines that carry the trigger signals to the components. Unfortunately, systems that use a star topology may be difficult to expand because additional trigger signal line connections may not be available for new components added to the system.